1. Field of the Invention
The present invention relates generally to a method and apparatus for use in the construction of precast, moment resisting frames of buildings. More particularly the invention concerns a method and apparatus for use in positioning high-strength cables within a precast, moment resisting frame made up of columns and beams that are interconnected by the high-strength cables.
2. Discussion of the Prior Art
In recent years great strides have been made in the design of high-rise buildings that resist lateral forces as well as vertical or gravity forces. One of the most successful prior art moment resisting frame designs is the design developed by the assignee of the present invention, namely Charles Pankow Builders, Ltd. This novel design includes moment resisting frames made up of columns and beams that are tied together in the horizontal direction by high-strength cables. These cables are entrained through a passageway located in the center of the beam so as to pass through the columns at the same elevation as the beam. In these structures, after the beam and column components are erected, the cables are entrained through the passageways and stretched or tensioned.
In the aforementioned types of prior art structures, tension within the stressed cables is typically transferred to the columns through wedge type anchors. The anchor imposes a clamping force on the columns transferring it through the interface between the columns and beam. This creates a compressive force through the moment resisting frame.
In the past, the installation of the cables in low-rise buildings was typically accomplished from outside of the building using lifts for access. However, for high-rise buildings, as for example buildings having over five or six floors, lift equipment is no longer capable of effectively providing this access. Nevertheless, in buildings where the frames terminate as the end of the side of the building, the cables must also be inserted from a point outside the buildings floor area. Additionally, high-rise buildings constructed in a regular floor-to-floor sequence have a need for routine cable installation techniques that accommodate the limited space availability inherent in such construction. To satisfy these needs, the apparatus of the present invention was developed. As will be better understood from the discussion that follows, this novel apparatus and the method associated with its use provide for the expeditious installation of the cables into the exterior spaces of the columns from inside rather than outside of the building.
It is an object of the present invention to provide an apparatus for positioning high-strength cables within a precast, moment resisting frame made up of interconnected columns and beams in which the columns have an outside face provided with an opening and a cable receiving passageway in communication with the opening. More particularly, is an object of the invention to provide a novel cable routing means for conveniently routing the cables from the interior of the moment resisting frame to the opening in the outside faces of the columns.
Another object of the invention is to provide an apparatus of the aforementioned character in which the cable routing means includes a curved tubular member that permits the cable to be inserted into an opening in the outside face of the column either from a first level within the structure that is substantially coplanar with the opening in the outside face of the column, or from a second level within the structure that is below the first level.
Another object of the invention is to provide an apparatus of the character described in the preceding paragraphs, which further comprises a locating plate that can be connected to the column so that an opening provided in the locating plate can be axially aligned with the opening and so that the distal end of the curved tubular member can be inserted into the opening.
Another object of the invention to provide an apparatus as described in the immediately preceding paragraph that further comprises a supporting stand that includes an upper portion adapted to support the proximal end of the curved tubular member.
Another object of the invention is to provide an apparatus of the class described that is of a simple construction, is easy use and is inexpensive manufacture.
Another object of the invention is to provide a method for conveniently inserting the high-strength cables into the opening in the outside faces of the columns from the interior, rather than the exterior of the moment resisting frame.
These and other objects of the invention can be achieved by the method and apparatus described in greater detail in the paragraphs would follow.